The background to these questions is that I've just sent a mobi/azw3 ebook I designed to the author. She says 'All this ebook technology [is] a big learning curve' and does not know what Kindle model she has or how to transfer the ebook to her reader. The paperwork she has mentions 'Kindle Black (Kindle 6).' I've attached a screenshot.

I have a Kindle Keyboard, and have told her the method I use to transfer eboks from my computer, but I don't know whether the same method will work on her reader.

Can some kind soul identify what model she has, and tell me how she should transfer the ebook I've emailedto her to her reader?

That's the basic Kindle, often referred to as the Kindle4B (B for balck) or KindleNT (NT for No Touch). The transfer methods are the same as they are for your Kindle 3/Keyboard. I've seen a few people call the Kindle Paperwhite a Kindle 6, but never heard this model called that.